Rotary pump for heating and cooling system

ABSTRACT

An absorption refrigeration system having a cooling and a heating mode of operation. A generator, an air-cooled condenser, a two-stage air-cooled absorber, a two-stage adiabatic evaporator and an air conditioning heat exchanger are connected to provide cooling. A heating mode of operation is provided wherein absorbent solution is heated in the generator and passed through the heat exchanger back to the generator to supply heat to a space being conditioned. The system embodies a plural trough solution scoop pump and a plural trough refrigerant or chilled water scoop pump mounted on a single shaft and driven by a single reversible motor to effect a change from cooling to heating and return.

United States Patent 1 Leonard, Jr.

[ 1 May 22, 1973 [54] ROTARY PUMP FOR HEATING AND [21] Appl. No.:147,492

Related US. Application Data [62] Division of Ser. No. 20,772, March 18,1970, Pat.

[52] 11.8. CI ..4l5/88 [51] Int. Cl. ..F04d 1/12, F04b 35/04 [58] Fieldof Search ..415/88, 89; 417/420; 310/104 [56] References Cited UNITEDSTATES PATENTS 211,347 1/1879 de Romilly ..415/89 2,124,914 7/1938Fottinger ..4l5/89 1,441,589 1/1923 Krogh ..4l5/89PrimaryExaminer-William L. Freeh Assistant Examiner-John T. WinburnAtt0rneyHarry G. Martin and J. Raymond Curtin [57] ABSTRACT Anabsorption refrigeration system having a cooling and a heating mode ofoperation. A generator, an aircooled condenser, a two-stage air-cooledabsorber, a two-stage adiabatic evaporator and an air conditioning heatexchanger are connected to provide cooling. A heating mode of operationis provided wherein absorbent solution is heated in the generator andpassed through the heat exchanger back to the generator to supply heatto a space being conditioned. The system embodies a plural troughsolution scoop pump and a plural trough refrigerant or chilled waterscoop pump mounted on a single shaft and driven by a single reversiblemotor to effect a change from cooling to heating and return.

3 Claims, 5 Drawing Figures PATENTEU MYZZIQYS 3 734,636

SHEET 1 [IF 2 I00 I 9a INVENTOR.

LOUIS H. LEONARD,JR.

y 99 BY M42. 9 ,g,

FIG. I ATTORNEY PATENTEB MAY 2 2 I975 SHEET 2 BF 2 INVENTOR. LOUIS H.LEONARD, JR.

ATTORNEY ROTARY PUMP FOR HEATING AND COOLING SYSTEM This application isa division of application Ser. No. 20,772, filed Mar. 18, 1970 now U.S.Pat. No. 3,608,628.

BACKGROUND OF THE INVENTION This invention relates to absorption systemswhich are capable of providing either refrigeration or heating. It isknown to employ centrifugal pumps to pump strong absorbent solution tothe absorber, weak absorbent solution to the generator, and refrigerantto the evaporator. Centrifugal pumps require that a positive head existin order to force the liquid into the impeller eye without flashing andvapor binding and this head requirement adds complexity and height tothe absorption machine and limits the application thereto of centrifugalpumps.

A heating and cooling absorption system has been proposed which utilizesone or more control valves, generally of the hermetic motorized orsolenoid type, to divert both the refrigerant and absorbent solutioninto the generator where the mixture is heated and passed to a suitableheat exchanger, when heating is desired. Such valves are relativelyexpensive and not totally reliable, and accordingly, it would bedesirable if this type valve could be completely eliminated from thesystem.

SUMMARY OF THE INVENTION A absorption machine is provided having acooling cycle comprising a generator, a condenser, an absorber, anevaporator, and a heat absorbing heat exchanger. The refrigerant iscooled in the evaporator and passed in heat exchange relation with theregion to be cooled by means of the heat absorbing heat exchanger. Onthe heating mode of operation, the passage of fluid through the systemis rearranged so that the absorbent solution is mixed with therefrigerant and heated in the generator. The heated mixture iscirculated through a suitable heat rejecting heat exchanger to provideheat to a desired region and is returned to the generator for reheating.Preferably, the heat absorbing heat exchanger of the cooling mode is thesame as the heat rejecting heat exchanger of the heating mode.

In accordance with this invention, there is also provided in theabsorption refrigeration system, fluid transfer apparatus forcirculating absorbent solution and refrigerant through the system. Thefluid transfer apparatus desirably takes the form of one or morehermetic housings enclosing a solution scoop pump and a refrigerantscoop pump, the troughs being supported for rotation on a shaft drivenby a reversible type motor. Driving the troughs of the scoop pumps inone direction causes solution and refrigerant to circulate through thesystem on the cooling cycle, and by simply reversing the motor, thesystem is automatically changed over to the heating cycle with thetroughs rotating in the reverse direction. In this manner, the use ofcentrifugal pumps and control 'valves for switching between cooling andheating operation are avoided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic flow diagram,partially in cross section, of a heating and cooling system inaccordance with this invention;

FIG. 2 is a cross section through a heating and cooling system takensubstantially along line IIII of FIG.

FIG. 3 is a cross section through a heating and cooling system takensubstantially along line III-III of FIG.

FIG. 4 is a cross section through a heating and cooling system takensubstantially along line IV-IV of FIG. 1; and

FIG. 5 is a cross section through a heating and cooling system takensubstantially along line VV of FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENT This invention will be describedwith respect to a preferred embodiment wherein a two-stage adiabaticrefrigerant evaporator and a two-stage air-cooled absorber are employedin the cooling mode of operation. However, this invention may beemployed in systems having any number of either adiabatic ornonadiabatic evaporator stages.

The preferred refrigerant is water and the preferred absorbent is anaqueous solution of lithium bromide, although otherabsorbent-refrigerant combinations, especially those including a lithiumhalide salt, may be employed instead. As used herein, a concentratedsolution of lithium bromide which is strong in absorbing power will bereferred to as strong solution. Weak solution is a dilute solution oflithium bromide which is weak in absorbing power. A suitable compound,such as octyl alcohol (Z-ethyI-n-hexanol) may be added to the solutionfor heat transfer promotion and corrosion inhibitors may be used ifdesired.

Referring to the drawings, the system comprises a generator 10, acondenser 11, a low pressure absorber 12, a high pressure absorber 13, alow temperature adiabatic evaporator 14, a high temperature adiabaticevaporator 15, an air conditioning heat exchanger 16, a solution heatexchanger 17, and fluid transfer apparatus generally designated by thelegend A. Heat exchanger 16 provides sensible heat exchange between coldliquid refrigerant and air being conditioned when the system isconnected to provide refrigeration and therefore functions as a heatabsorbing heat exchanger. If a nonadiabatic conventional evaporator isemployed, heat exchanger 16 may be located in the evaporator.

Generator 10 may be of the known shell-and-tube type heated by a fuelburner, or in the alternative, may utilize steam or hot water as theheating fluid. Weak solution is supplied to generator 10 and boiledtherein to concentrate the solution in the cooling mode of operation,the pumping being done by fluid transfer apparatus A.

Low pressure absorber 12 comprises a plurality of vertically disposedfinned absorber heat exchange tubes 20 connected at their upper ends bya low pressure vapor header 21 and at their lower ends by a low pressureliquid header 22. Strong solution overflows the open upper ends ofabsorber tubes 20 and passes downwardly along the inner surfaces of theabsorber tubes while absorbing refrigerant vapor therein. The heat ofthe absorption process is rejected to ambient air passed over theexterior surfaces of absorber tubes by fan 23. The absorbent solution issomewhat diluted by absorption of refrigerant vapor in tubes 20, so thatthe solution collected in low pressure liquid header is of intermediateconcentration and drains therefrom into fluid transfer apparatus A andis pumped to high pressure vapor header 24 of high pressure absorber 13.

High pressure absorber 13 comprises a plurality of finned verticalabsorber heat exchange tubes 25 joined at the upper ends by header 24and at their lower ends by high pressure liquid header 26. Intermediateabsorbent solution overflows the upper open ends of absorber tubes 25and passes downwardly along the interior surfaces of the absorber tubeswhile refrigerant vapor is being absorbed therein. The heat of theabsorption process is rejected from high pressure absorber 13 to ambientair passed over the exterior surfaces of absorber tubes 25 by fan 27.

Absorbent solution passing downwardly through absorber tubes 25 isfurther diluted by the absorption of refrigerant vapor therein so thatthe absorbent solution collected in high pressure liquid header 26 isweak in absorption power. The weak solution passes from liquid header 26through drain conduit 28 into fluid transfer apparatus A from which itis pumped through the interior of the tubes of solution heat exchanger17 and through weak solution passage 29 into generator forreconcentration therein.

Refrigerant vapor is formed in generator 10 by the boiling of absorbentsolution. This refrigerant vapor passes from generator 10 to refrigerantvapor header 30 of condenser 11 through refrigerant vapor conduit 31.Refrigerant condenser 11 comprises a plurality of vertically disposedfinned tubes 32 connected at their upper ends by vapor header 30 and attheir lower ends by refrigerant condensate header 33. Preferably,condenser 11 is located to receive air passing over the tubes inabsorber 13 in order to utilize the absorber fans for passage of coolingair over the condenser. The refrigerant condensate formed in condenser11 passes from header 33 through condensate passage 34 having adownwardly extending loop or trap 35 connected thereto and throughcondensate conduit 36 to fluid transfer apparatus A to be pumpedtherefrom through isolation loop 37 to high temperature adiabaticevaporator through spray header 38 therein.

High temperature adiabatic evaporator 15 preferably comprises a shell 39mounting therein a baffle member 40 for directing the vapor dropletsdischarged from spray header 38 into conduit 41 communicating with lowtemperature adiabatic evaporator 14. A small quantity of refrigerant isevaporated from refrigerant passing through high temperature evaporator,thereby flash-cooling the remaining refrigerant. The cooled refrigerantpasses from high temperature evaporator 15 to low temperature evaporator14 through refrigerant passage 41 which has connected thereto sprayheader 42 for discharging liquid refrigerant against baffle member 43disposed within shell 44 oflow temperature evaporator 14. Withinevaporator shell 44 a further small quantity of refrigerant isevaporated which results in flash-cooling the remainder of refrigerantpassing therethrough to a still lower temperature. In all, only about 1percent of the total refrigerant flowing through adiabatic evaporators14 and 15 need be evaporated to satisfactorily flash-cool the remaining99 percent. It is preferred to employ adiabatic evaporators in which therefrigerant is flash-cooled and no external heat is added; however,conventional single or multi-stage evaporators having heat absorbingheat exchangers therein may be employed, if desired.

The cold refrigerant then passes from low temperature evaporator 14through an isolation loop 45 and drains into fluid transfer apparatus Afrom which it is pumped through conduit means 46 up through heatabsorbing heat exchanger 16 having in association therewith fan means 47for passing air to be conditioned over the heat exchanger. Heatexchanger 16 passes cold liquid refrigerant in heat exchange relationwith the air passing thereover to cool the air which constitutes arefrigeration load in the cooling mode of operation. After absorbingheat from the air being cooled, the warmed liquid refrigerant drainsdown through conduit means 48 connected to heat exchanger 16 and intofluid transfer apparatus A from which it is pumped through isolationloop 37 back to the high temperature evaporator.

Prior to describing the heating mode of operation, the fluid transferapparatus A will be described. The apparatus A may comprise a hermetichousing 50 mounting hermetic magnetic drive means 51 connected at oneend by shaft means 52 to a single reversible motor 53 equipped witheither a manual or automatic switching means 54. The shaft means 52 atthe opposite end of the magnetic drive means 51 is journaled in solutionlubricated radial and thrust bearing means 55 and supports on oppositesides of the bearing means a double-trough chilled water scoop pump P-1'and a triple-trough solution scoop pump P-2.

The pump P-l includes a central partition member supported by the driveshaft 52, the partition having connected thereto along its circumferencean annular wall member 61 having radially inwardly directed wallportions 62 and 63 to define with the partition member 60 a pair ofrefrigerant circulation chambers C-1 and C-2. Leading into chamber C-lis inlet passage portion 64 forming a part of conduit 48 connected toair conditioning heat exchanger 16. Passage 64 functions as a drain linewhen the system is on the cooling mode of operation and as a pump inletpassage when the system is on the heating cycle. An inlet orifice 65 ofconduit 36 passes refrigerant from the condenser header 33 to chamberC-l. Eduction orifice 66 of conduit 67 passes liquid refrigerant fromchamber C-l to high temperature evaporator 15 through circulation loop37.

Chamber G2 has therein a passage 70 forming a part of conduit means 46leading to air conditioning heat exchanger 16 and which conduit portionperforms a dual function. Passage 70 carries cool refrigerant pumped tothe heat exchanger 16 when the system is on the cooling mode ofoperation and performs a drain function when on the heating cycle. Alsoin chamber O2 is conduit portion 71 leading through sump 111 andcirculation loop 45 to low temperature evaporator 14 to drain coldliquid refrigerant into this chamber. There is also in chamber C-2conduit portion or eduction orifice 72 of conduit means 73 fortransferring refrigerant through check valve means 74 to the generator10 when the system is providing heating.

Scoop pump P-2 comprises a central partition member secured to driveshaft 52 and mounting along its circumference an annular wall member 81provided with radially inwardly directed wall portions 82 and 83 todefine a pair of solution circulation chambers C-3 and C-4. Alsoattached to the partition member 80 is an annular wall member 84circumferentially inwardly spaced from wall member 81 and havingattached thereto a radially inwardly extending annular wall portion 85defining with partition 80 and wall member 84 a solution circulationchamber C-5.

Solution circulation chamber C-3 has leading thereto conduit portion 86of conduit means 28 for transferring into this chamber weak solutiondraining from high pressure liquid header 26 of high pressure absorber13. The weak solution is pumped from chamber C-3 by scoop 87 of conduitmeans 88 and passed through check valve 89, solution heat exchanger 17and weak solution passage 29 into generator for reconcentration therein.

Solution circulation chamber C-4 has three conduit portions leadingthereto. The first conduit 90 is a double function drain line forming apart of conduit means 91 communicating with solution heat exchanger 17and conveying strong solution from generator 10 to chamber C-4, fromwhich it is pumped by eduction orifice 92 of conduit means 93 andtransferred thereby to low pressure absorber 12. The dual function line90 drains solution into chamber C-4 on both the cooling and heatingmodes of operation. On the heating cycle, solution is also pumped fromchamber C-4 by eduction orifice 94 of conduit means 95 and transferedthrough check valve 96 and drain conduit portion 97 into chamber C-lfrom which it is pumped to air conditioning heat exchanger 16 by meansof eduction orifice 64 of conduit means 48. The conduit means 95 andassociated eduction orifice 94 and drain conduit portion 97 are inactivewhen the system is on the cooling cycle as will be subsequentlyexplained.

Solution circulation chamber C-5 has leading thereto drain conduitportion 98 of conduit means 99 communicating with low pressure liquidheader 22 of low pressure absorber 12 for transferring to chamber C-5intermediate solution which is pumped therefrom by eduction orifice 100of conduit means 101 and passed to high pressure absorber l3.

Generator 10 has connected thereto a solution bypass conduit 102 throughwhich approximately 80 percent of the solution flows to conduit 91 whenthe system is on the heating mode of operation, the remaining solutionon the heating cycle passing through conduit 103 which passes all of thefluid when the system is on the cooling mode of operation.

As will be seen from FIG. 2, eduction orifice 64 of passage 48 faces ina counterclockwise direction in chamber C-1 and eduction orifice 66 ofpassage 67 faces in a clockwise direction in the chamber. Consequently,rotation of the scoop pump pan in a counterclockwise direction causesliquid to be impelled into eduction orifice 66 while orifice 64 merelytrails in the wake of the preceding scoop. Similarly, when the scooppump is rotated in a clockwise direction, eduction orifree 66 merelytrails in the wake of the passage 48 containg eduction orifice 64 intowhich liquid is impelled. In FIG. 3, eduction orifices 70 and 72 face ina counterclockwise and clockwise direction respectively and areconsequently only operative in the correspondingly opposite direction ofrotation of pan or chamber G2 which is axially spaced from pan orchamber C-l.

As shown in FIG. 4, solution chamber C-3 is arranged with eductionorifice 87 facing in a clockwise direction in order thatcounterclockwise rotation of the pan causes liquid to be impelled intothe chamber, whereas the opposite rotation does not result in pumping.

FIG. 5 illustrates a cross section through the concentric pans formingscoop pumps C-4 and C-5. Eduction orifices 92 and 94 face in a clockwiseand a counterclockwise direction respectively, to receive liquid thereinonly when the pan is rotated in a correspondingly opposite direction. Inboth instances, liquid is supplied by drain line 91 through orificewhich is preferably disposed approximately 180 removed from scoops 92and 94 to provide a maximum resistance time for the liquid in the pan sothat it will be accelerated to a relatively high velocity beforereaching the scoop. Intermediate solution chamber C-5 contains only aclockwise facing eduction orifice operative only on counterclockwiserotation of the pan to receive liquid. It is preferred to locate inletorifice 98 of passage 99 greater than from the eduction orifice topermit for acceleration of the liquid to its maximum velocity beforebeing received by the scoop.

During cooling operation of the absorption system, motor 53 is rotatedin a counterclockwise direction causing scoops 66, 70, 87, 92 and 100 tobe operative while scoops of eduction orifices 64, 72 and 94 do not pumpliquid but trail in the wake of the preceding scoop. With motor 53rotating in a counterclockwise direction, strong solution drains fromgenerator 10 through passage 103, heat exchanger 17 and strong solutionpassage 91 into strong solution chamber C-4. The strong solution ispicked up by eduction orifice 92 and pumped through passage 93 to vaporheader 21 of low pressure absorber stage 12. The strong solution passesdownwardly through the absorber tubes 20, absorbing refrigerant vapor,which dilutes the strong solution. The intermediate strength solution iscollected in liquid header 22. The intermediate solution passes throughsolution passage 99 and drains through inlet orifice 98 into chamberC-5. The rotation of scoop pump pan forming chamber C-5 causes theintermediate solution to be picked up by eduction orifice 100 and pumpedthrough passage 101 to vapor header 84 of high pressure absorber stage13. The absorbent solution passes downwardly through absorber tubes 25and is further diluted by absorption of refrigerant vapor. Weak solutionis collected in liquid header 26 and passes through weak solutionpassage 28 from which it drains through orifice 86 into weak solutionchamber C-3. The weak solution is picked up by eduction orifice 87 andpumped through weak solution passage 88, heat exchanger 17, and weaksolution passage 29 to generator 10 for reconcentration therein.

The refrigerant vapor formed by generator 10 passes through vaporpassage 31 to condenser 11 where it is condensed by heat exchange withambient air. The refrigerant condensate is collected in condensateheader 33, passes through passage 34, isolation loop 35 and condensatepassage 36 from which it drains into chamber C-l through orifice 65.Rotation of the pan forming chamber C-l in the counterclockwisedirection causes the liquid refrigerant to be picked up by scoop 66 andpassed through passage 67, isolation loop 37 and spray header 38 intohigh temperature evaporator 15. The refrigerant is flash-cooled in thehigh temperature evaporator and the cool remaining liquid drains throughpassage 41 and spray header 42 into low temperature evaporator 14. Theliquid refrigerant is further flash-cooled in the low temperatureevaporator and the cold remaining refrigerant passes therefrom throughloop 45 into sump 111. The cold refrigerant drains from sump 111 throughdrain orifice 71 into chamber C-2. The cold liquid is picked up byeduction orifice 70.

In accordance with this invention, the system is switched from coolingto heating mode operation by simply reversing the direction of motor 53so that it rotates in a clockwise direction. When the scoop pump pansrotate in a clockwise direction, scoops 64, 72 and 94 are operative topump liquid, and scoops 66, 70, 87, 92 and 100 do not have liquidimpelled into them. Warm solution from generator continues to passthrough passage 103, heat exchanger 17, and passage 91 from which itdrains through orifice 90 into solution chamber C4. The hot solution isthen picked up by orifice 94 and passed through passage 95 andtransferred through check valve 96 to chamber C-l into which it drainsfrom orifice 97. The hot solution discharged into chamber C-] is pickedup by orifice 64 and passes through passage 48 into air conditioningheat exchanger 16 to provide heating to the desired location. Thesolution is then returned through passage 46 having orifice 70 thereinto chamber C-2. This solution is impelled into orifice 72 of passage 73through which it is pumped past check valve 74 into generator 10 forreheating.

It will be noted that the hot solution is substantially diluted byhaving been mixed with refrigerant in its passage through chambers C-1and C-2, so that it forms a solution having a relatively low freezingpoint. In addition, the volume of solution being circulated to thegenerator is increased by being mixed with the refrigerant in the systemso that the level in the generator will rise and overflow the top ofpassage 102. Thus, hot solution will continue to be supplied from thegenerator into chamber C-4 through both passages 103 and 102 while thesystem is operating in the heating mode.

When it is desired to return the system from the heating mode to thecooling mode of operation, the direction of motor 53 is again reversed,so as to drive the scoop pump pans in a counterclockwise direction.While the direction of liquid flow in the system will be the same aspreviously described for cooling operation, it will be apparent that themixture of refrigerant and absorbent solution must be separated toprovide full cooling capacity. This is achieved by providing arefrigerant sump 111 in refrigerant passage 45 and an absorbent sump 110in solution passage 28 with an overflow passage 112 extending betweenthe two sumps. As long as the volume of refrigerant evaporated is low,due to having substantial absorbent mixed therein, the level ofrefrigerant in sump 111 will be relatively high. Consequently, liquidwill drain from sump 111 through passage ll2 into sump 110 from which itwill pass through chamber C-S to generator 10 where refrigerant will beseparated therefrom. The bleeding of refrigerant to the generatorthrough passage 112 will continue until the refrigerant has becomesufficiently purified to sustain the refrigeration load on the system,thereby providing the desired refrigeration capacity.

The invention described herein utilizes the unique and specialproperties of a scoop pump to effectively pump liquid in an absorptionrefrigeration system in the absence of a suction head and in thepresence of noncondensable gases or other vapors without injuriouseffect to the pump. Furthermore, by utilizing scoops or eductionorifices facing different directions in the pump, it is possible toswitch the fluid flows in the system to provide either heating orcooling without the use of expensive reversing valves by simplyreversing the direction of rotation of the scoop pump pans. Accordingly,there is provided an improved absorption system and a scoop pump capableof operating as both a pump and a valve for supplying liquid to one ormore selectable locations depending on the direction of rotation of thepump.

While preferred embodiments of this invention have been described forpurposes of illustration, it will be appreciated that the invention maybe otherwise embodied within the scope of the following claims.

I claim:

1. A combined pump and valve apparatus for controlling the flow ofliquid in a system, said apparatus comprising a housing, a rotatable panmounted for rotation therein, a reversable electric motor includingmeans to reverse the direction of rotation of said electric motor, saidelectric motor being connected to retate said pan in a directioncorresponding with the direction of rotation of the motor; a firststationary scoop extending into said pan having an eduction orificefacing in one direction of rotation of said pan; a second stationaryscoop extending into said pan having an eduction orifice facing oppositesaid one direction of rotation of said pan; a stationary dischargeconduit extending toward said pan and being positioned for dischargingliquid therein; and means for actuating said electric motor to run insaid one direction of rotation when liquid flow through said secondscoop is desired and to actuate said electric motor to run in the otherdirection when liquid flow through said first scoop is desired, wherebyliquid from said discharge conduit is selectively pumped into eithersaid first or said second scoop depending on the selected direction ofrotation of said reversable electric motor.

2. A combined pump and valve assembly as defined in claim 1 wherein saidscoop pump pan is axially divided into a plurality of scoop pump pans,each having a scoop and an inlet passage for pumping a plurality ofliquid streams.

3. A combined pump and valve assembly as defined in claim 1 wherein saidscoop pump pan is divided into a plurality of concentric scoop pumppans, each having a scoop and an inlet passage for pumping a pluralityof liquid streams.

1. A combined pump and valve apparatus for controlling the flow ofliquid in a system, said apparatus comprising a housing, a rotatable panmounted for rotation therein, a reversable electric motor includingmeans to reverse the direction of rotation of said electric motor, saidelectric motor being connected to rotate said pan in a directioncorresponding with the direction of rotation of the motor; a firststationary scoop extending into said pan having an eduction orificefacing in one direction of rotation of said pan; a second stationaryscoop extending into said pan having an eduction orifice facing oppositesaid one direction of rotation of said pan; a stationary dischargeconduit extending toward said pan and being positioned for dischargingliquid therein; and means for actuating said electric motor to run insaid one direction of rotation when liquid flow through said secondscoop is desired and to actuate said electric motor to run in the otherdirection when liquid flow through said first scoop is desired, wherebyliquid from said discharge conduit is selectively pumped into eithersaid first or said second scoop depending on the selected direction ofrotation of said reversable electric motor.
 2. A combined pump and valveassembly as defined in claim 1 wherein said scoop pump pan is axiallydivided into a plurality of scoop pump pans, each having a scoop and aninlet passage for pumping a plurality of liquid streams.
 3. A combinedpump and valve assembly as defined in claim 1 wherein said scoop pumppan is divided into a plurality of concentric scoop pump pans, eachhaving a scoop and an inlet passage for pumping a plurality of liquidstreams.